I started my son off in Happy Heiny OS and thought I would love them, and I loved everything about them EXCEPT for the excessive amount of diaper between his legs. So we switched to sized pocket diapers instead. Imagine a XL Pocket diaper amount of between leg fabric on a small diaper, I felt like my son always looked like a sumo wrestler. IMO, dont go OS until little one is older, like probably a year or so.
Here is my son in his OS at 3 months probably about 13 pounds